Introduced taxa in disturbed ecosystems

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Abstract

In the literature, introduced taxa are assumed to
be present, more abundant, and occupy greater physical space in
portions of ecosystems disturbed by human activity. This study
tested this principle in two sites, Short Hills provincial Park
("SHU) and Backus Woods ("B~l"). spatial distribution of
introduced taxa of vegetation, isopods, and earthworms was
determined with the runs test along 300m transects encompassing
gradients of anthropogenic disturbance severity. The hypothesis
was that introduced taxa would be aggregated along these
transects; the null hypothesis was that they would not be
aggregated.
The null hypothesis was rejected for the
introduced taxa as a unit, and vegetation and earthworms
individually. Introduced taxa were aggregated along 53.33%
(N~30) and 57.14% (N~21) of the transects in SH and BW
(respectively). Introduced vegetation (90.00%, N~10 and
100.00%, N~7) and earthworms (50.00%, N~10 and 50.00%, N~8)
were also significantly aggregated within the sites. Introduced
isopods, however, were not significantly aggregated at either
place (20. 00%, N-=10 and 16. 67%, ~J~6).
This study demonstrated that introduced taxa are
aggregated within ecosystems disturbed by human activity.
However, since introduced isopods were not significantly
aggregated it was also shown that taxa respond differently.